JDK-8039921: SHA1WithDSA with key > 1024 bits not working

Atsuhiko Yamanaka atsuhiko.yamanaka at gmail.com
Fri Sep 19 00:56:02 UTC 2014


Thank you for your quick response,

On Fri, Sep 19, 2014 at 9:04 AM, Valerie Peng <valerie.peng at oracle.com> wrote:
>                                                                                                   Do you have any
> more info such as CA certs using large DSA keys with SHA1withDSA signature
> algorithm, etc.?

Our problem has appeared in SSH2 connections, not in CA certs.

On SSH2 protocol, the key exchange will be used to share the secret
between client
and server, and that secret will be used to encrypt packets.
SHA1WithDSA has been
used to confirm if the secret is successfully shared or not.  The
SSH2's RFCs have defined
some methods for key-exchanges.

RFC4419[1] has defined "diffie-hellman-group-exchange-sha1" at its
Section 3, and it has
allowed to use keys between 1024 and 8192.  And also, RFC4253[2] has
defined "diffie-hellman-group1-sha1".  In that key-change method, 1024
bit-length key will be used, but some sshds have been using
the longer keys.  It seems those sshds have been widely used
unfortunately, and pure java SSH2 clients
have not been able to connect to them in using Java8's SunJCE.

I hope this is the expected answer for your question.

[1] http://tools.ietf.org/html/rfc4419
[2] http://tools.ietf.org/html/rfc4253#section-8.1

Atsuhiko Yamanaka
SENDAI, MIYAGI 980-0014 Japan.
Tel +81-22-723-2150
Skype callto://jcraft/
Twitter: http://twitter.com/ymnk
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